Punch



Aug. 10, 1948. PRESTER 2,446,848

PUNCH Filed Nov. 26, 1946 Im'eutor Army? Pmsiw Attoeys Patented Aug. 10,1948 UNITED S TAT ES PATENT O F F I CE PUNCH iirthur Prester,Philadelphia, Pa.

Application November 26, 1946, Serial No. 712,460

1 Claim. 1

Tliisi'invention refers generally to punches, and more particularly to asmall hand tool operated icy the manual compression of a spring, andsometimes referred to as an automatic punch because the use of ahand-held hammer is not required, the percussion member being a smallinternal hammer impelled by the spring against the pointed head of thepunch.

An object of this invention is to provide such a tool which will beparticularly well adapted for use as a center punch for use in layingout material preparatory to drilling, and for other like uses.

Another object of this invention is to provide an automatic punch whichmay be made with a light spring and a sharp, long tapered point adaptingthe tool for use as a prick punch, for such use as laying out templetsin lofting.

Another object of this invention is to provide a tool of this type whichis simplified in structure to a greater degree than currently useddevices, these other devices being usually equipped with catches andother complicated structure frequently becoming inoperative.

A last object to be specifically mentioned is to provide such a tool ina form which is practicable and inexpensive to manufacture, simple andvery convenient to use, and which is compact and sturdy and will giveefficient and durable service.

With these and other objects in view as will appear hereinafter, thisinvention consists of certain novel features and construction, andcombination and arrangement of parts as will be hereinafter described indetail and particularly set forth in the appended claim, reference beinghad to the accompanying drawings which form a material part of thisapplication, and in which:

Figure 1 is a perspective view of the improved punch showing theretracted position of the stem handle in dash line and indicating themethod of operation, to amplify this disclosure;

Figure 2 is a side elevation of this invention; and

Figure 3 is a vertical sectional view, taken on the line 3-3 in Figure2, with portions being shown in elevation.

Similar characters of reference refer to similar or identical partsthroughout the several views of the drawings.

Referring now to the drawings in detail, which drawings illustrate apreferred embodiment of this invention, it will be noted that thestructure includes only four parts. The portion by which this tool isgrasped by the hand is made in the form of a sleeve 10, which isinteriorly threaded at the end i2, and at the other end thereof isprovided with a cap M which is perfonatedlas at it. This perforated acapprovides a bearing surface for the reciprocaitively mounted handlestemportion 18 of the hammer, the head portion 20 of which is of a diameterslightly less than the interior diameter of the sleeve ID. The terminalportion of the stem handle l8 may be knurled, as shown, better adaptingthis stem handle to be grasped by the fingers and withdrawn a shortdistance, compressing the helical spring 22 between the upper face ofthe hammer 20 and the inside of the cap I4.

This spring 22 encloses a major portion of the stem handle l8 and willbe made considerably stronger when the device is to be used as a centerpunch than when the device is made in lighter form for use as a prickpunch.

A pointed head 24, preferably of an exterior diameter equal to that ofthe sleeve 10, is provided with a projecting portion 26 which isexteriorly threaded to engage the threaded end l2 of the sleeve, and theend of this projection 26 is beveled so that a certain amount of peeningor expansion of this part as a result of the percussive action of thehammer head 20 will not cause the threaded portion 26 to bind within thesleeve, making the pointed head 24 difiicult to remove. The lower edgeof the head of the hammer is also beveled for the same reason and alsoto make the hammer more freely reciprocative within the sleeve.

Certain useful modifications of this illustrated embodiment of thisinvention will occur to machinists and loftsmen and others using thedevice, such as the mode of securing the pointed head 24 to the sleeveID, the provision of an insert bearing in the apertured cap l4, and theprovision of a stem handle in two parts, but it is contended that theseand other like modifications are within the scope and spirit of thisinvention and within a proper interpretation of the claim hereunderappended.

In View of the foregoing disclosure of the structural details of thisdevice, the method of operation thereof will be clear. When the deviceis to be used as a center punch, the angle of the pointed head 24 willbe approximately 45 and the point will, of course, be hardened, theindentations in the work being made simply by placing the point at thedesired position; retracting the hammer head 20 by withdrawing the stemhandle H3 at short distance and allowing the same to snap back, strikingthe face of the beveled portion 28 of the pointed head 24. When thedevice is used as a prick punch, a more pointed head 24 and a lightersprin 22 will normally be provided, but in the event that a center punchis adapted for use as a prick punch by merely sharpening the head 24, itwill be necessary only to withdraw the stem handle [8 a very shortdistance, thus lessening the percussive force of the hammer 20. It isthought that other uses and adaptations of this device need not bedetailed here, the above being adequately illustrative of theconstruction and method of operation of this invention.

Though there has been shown a particular embodiment of this invention,this application is not limited to this particular embodiment, but it isdesired to include in the scope of this invention the construction,combination and arrangement of parts substantial-1y as set forth in theappended claim. 7

Having thus described this invention, what is claimed as new and desiredto be secured by Letters Patent is:

A hand tool of the character described including a sleeve member, apointed head secured to one end of said sleeve, a hammer reciprocativelymounted within said sleeve and having a 4 handle portion extendingoutside said sleeve, and a spring adapted to urge said hammer in onedirection, said sleeve being threaded at one end thereof to engage acorrespondingly threaded portion of said head and having a cap at theother end thereof, and said spring being of helical type and compressedbetween said hammer and said cap within said sleeve, said cap beingperforated and integral with said sleeve and said handle having a stemextending within said helical spring and through said apertured cap andadapted to be pulled to compress said spring.

ARTHUR PRESTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Allen Dec. 17, 1940

